CN213783652U - Monitoring circuit, constant current drive device and car light - Google Patents
Monitoring circuit, constant current drive device and car light Download PDFInfo
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- CN213783652U CN213783652U CN202022732264.XU CN202022732264U CN213783652U CN 213783652 U CN213783652 U CN 213783652U CN 202022732264 U CN202022732264 U CN 202022732264U CN 213783652 U CN213783652 U CN 213783652U
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Abstract
The utility model relates to a monitoring circuit, constant current drive arrangement and car light, include: the filtering unit is connected with the second pin and is used for filtering interference signals except pulse signals in the output signals of the second pin; the energy storage unit is connected with the first pin, and the MCU charges the energy storage unit through the first pin when the first pin outputs a monitoring enabling signal; the first electric connection end of the switch unit is connected with the filtering unit, the second electric connection end of the switch unit is grounded, and the third electric connection end of the switch unit is connected with the energy storage unit; the switch unit is used for controlling the connection or disconnection between the second electric connection end and the third electric connection end according to a signal input by the first electric connection end; and the output end of the logic trigger unit is used for outputting a level signal opposite to the input end of the logic trigger unit, monitoring whether the MCU fails or not, and generating a falling edge signal after the MCU fails, so as to trigger the entry of a failure safety alarm.
Description
Technical Field
The utility model relates to a power electronic technology field especially relates to a monitoring circuit, constant current drive arrangement and car light.
Background
At present, in the field of Constant Current control, with the increase of complexity of a system, a role of a Microcontroller (MCU) in a load Constant Current Drive Module (LDM) becomes more and more important. With the introduction of MCUs, there is a concern about software stability and stability of the MCUs themselves. Therefore, each large host plant requires a Fail-Safe (Fail-Safe) function for MCU failures (hardware failures and soft failures) to be added to the LDM.
The DC-DC constant current or linear constant current control chip needs to receive a level signal of a falling edge from a Fail-Safe pin to trigger entering a Fail-Safe mode. However, since the MCU no longer has control capability after failure, it cannot be guaranteed that a level signal of a falling edge can be generated in all failure modes, resulting in a decrease in system reliability.
SUMMERY OF THE UTILITY MODEL
In view of the above, it is desirable to provide a monitoring circuit, a constant current driving device and a vehicle lamp.
A monitoring circuit is used for being connected with an MCU (microprogrammed control unit) and generating a falling edge signal after the MCU fails to serve as a failure safety alarm signal, wherein the MCU comprises a first pin and a second pin, the first pin is used for outputting a monitoring enabling signal when the MCU needs to be monitored whether the MCU fails, the second pin is used for outputting a pulse signal and stopping outputting the pulse signal when the MCU fails, and the pulse signal is a periodic turnover level signal; the monitoring circuit includes:
the filtering unit is connected with the second pin and is used for filtering interference signals except the pulse signals in the output signals of the second pin;
the energy storage unit is connected with the first pin, and the MCU charges the energy storage unit through the first pin when the first pin outputs the monitoring enabling signal;
the first electric connection end of the switch unit is connected with the filtering unit, the second electric connection end of the switch unit is grounded, and the third electric connection end of the switch unit is connected with the energy storage unit; the switch unit is used for controlling the connection or disconnection between the second electric connection end and the third electric connection end according to a signal input by the first electric connection end; and
and the output end of the logic trigger unit is used for outputting a level signal opposite to the input end of the logic trigger unit.
In one embodiment, the MCU further includes a third pin, where the third pin is a reset pin of the MCU, and the monitoring circuit further includes:
the trigger output unit is connected with the output end of the logic trigger unit and is used for outputting the fault safety alarm signal when the output end of the logic trigger unit outputs a low level;
the reset unit is connected with the output end of the logic trigger unit, connected with the third pin and used for outputting a reset signal to the third pin when the output end of the logic trigger unit outputs a low level;
and the reverse isolation unit is connected between the output end of the logic trigger unit and the trigger output unit, is connected between the output end of the logic trigger unit and the reset unit, and is used for performing reverse isolation on the trigger output unit and the reset unit when the output end of the logic trigger unit outputs a high level.
In one embodiment, the filtering unit includes a filtering capacitor, and the filtering capacitor is connected between the first electrical connection terminal of the switch unit and the second pin;
the monitoring circuit still includes prevents the saturation diode, prevent the anode ground connection of saturation diode, prevent the saturation diode the cathode with filtering electric capacity is connected and with the first electricity of switch element connects, prevent the saturation diode and be used for preventing lose effect after the filtering electric capacity is saturated.
In one embodiment, the monitoring circuit further comprises:
and the protection resistor is connected between the first electric connection end of the switch unit and the filtering unit and used for limiting the current of the switch unit.
In one embodiment, the switch unit includes a triode, a base of the triode is a first electrical connection terminal of the switch unit, an emitter of the triode is a second electrical connection terminal of the switch unit, and a collector of the triode is a third electrical connection terminal of the switch unit.
In one embodiment, the energy storage unit comprises a first voltage division resistor, an energy storage capacitor and a second voltage division resistor; one end of the first divider resistor is connected with the first pin, the other end of the second divider resistor is connected with one end of the energy storage capacitor, the other end of the energy storage capacitor is grounded, one end of the second divider resistor is connected between the energy storage capacitor and the first divider resistor, and the other end of the second divider resistor is grounded;
the resistance value of the second voltage-dividing resistor is larger than that of the first voltage-dividing resistor.
In one embodiment, the monitoring circuit further comprises:
the discharge resistor is connected between the input end and the output end of the logic trigger unit, and the reverse isolation unit is also connected between the output end of the logic trigger unit and the discharge resistor; when the output end of the logic trigger unit outputs a low level, the discharge resistor is used for shortening the discharge time of the energy storage unit, and when the output end of the logic trigger unit outputs a high level, the reverse isolation unit performs reverse isolation on the trigger output unit, the reset unit and the discharge resistor;
wherein the resistance value of the discharge resistor is smaller than that of the first voltage dividing resistor.
In one embodiment, the reverse isolation unit includes:
the anode of the first isolation diode is connected with the reset resetting unit, and the cathode of the first isolation diode is connected with the output end of the logic triggering unit;
the anode of the second isolation diode is connected with the trigger output unit, and the cathode of the second isolation diode is connected with the output end of the logic trigger unit;
and the anode of the third isolation diode is connected with the discharge resistor, and the cathode of the third isolation diode is connected with the output end of the logic trigger unit.
In one embodiment, the logic trigger unit comprises a schmitt reverse trigger.
In one embodiment, the MCU further comprises a power pin;
the reset unit comprises a first pull-up resistor, one end of the first pull-up resistor is connected with the power pin, and the other end of the first pull-up resistor is connected with the reverse isolation unit and the third pin;
the trigger output unit comprises a second pull-up resistor, one end of the second pull-up resistor is connected with the power pin, and the other end of the second pull-up resistor is connected with the reverse isolation unit.
In one embodiment, the charging time of the energy storage unit is greater than twice the period of the pulse signal.
A constant current driving device comprises an MCU, a constant current driving module and a monitoring circuit as described in any one of the above; the MCU is connected with the constant current driving module and the monitoring circuit, and the constant current driving module is also connected with the monitoring circuit; the monitoring circuit is used for monitoring whether the MCU breaks down and outputting a falling edge signal to the constant current driving module to carry out fault safety alarm when the MCU breaks down.
A vehicle lamp, comprising:
an LED module; and
the constant current driving device is connected with the LED module and is configured to drive the LED module to light up.
The monitoring circuit, the constant current driving device and the vehicle lamp can monitor whether the MCU fails or not, and can generate a falling edge signal after the MCU fails, so that the MCU is triggered to enter a failure safety alarm.
Drawings
FIG. 1 is a block diagram of a monitoring circuit according to an embodiment;
fig. 2 is a block diagram of a constant current driving device according to an embodiment;
FIG. 3 is a circuit diagram of a monitoring circuit in an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In the description of the present application, it is to be understood that the terms "center", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner" and "outer" etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application. Further, when an element is referred to as being "formed on" another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.
Fig. 1 is a block diagram of a monitoring circuit in an embodiment. Fig. 2 is a block diagram of a constant current driving device in an embodiment. With reference to fig. 1 and 2, the monitoring circuit 120 is configured to be connected to the MCU110 and generate a falling edge signal as a fail-safe alarm signal after the MCU110 fails, so as to trigger a fail-safe alarm. The MCU includes a first pin a1, a second pin a 2. The first pin a1 is used to output a monitoring enable signal when the MCU110 needs to be monitored for a fault, the monitoring circuit 120 is connected to the first pin a1, and the monitoring circuit 120 starts to monitor the MCU for a fault after receiving the monitoring enable signal output by the first pin a1, for example, the monitoring enable signal may be a high level signal, and when the MCU110 does not need to be monitored for a fault, the electrical connection terminal of the monitoring circuit 120 connected to the first pin a1 may be in a low level or high impedance state, and the monitoring for the fault of the MCU110 is stopped. The second pin a2 is used to output a pulse signal, which is a periodic inverted level signal, and stop outputting the pulse signal after the MCU110 fails. When the monitoring circuit 120 starts to monitor the MCU110 for a fault, and the electrical connection terminal of the monitoring circuit 120 connected to the second pin a2 receives a pulse signal, it indicates that the MCU110 is working normally, and when the pulse signal is stopped, it indicates that the MCU110 is faulty. The second pin a2 may be a General-purpose input/output interface (GPIO) with non-auto-inversion, and the second pin a2 is controlled by software to output a high level or a low level and periodically invert the high level or the low level to generate a pulse signal, because the GPIO pin with non-auto-inversion is inverted by software control, after the MCU110 has a software fault or a hardware fault, the second pin a2 stops level inversion, i.e., stops outputting the pulse signal, so that any fault of the MCU110 can be detected by the monitoring circuit 120.
Specifically, the monitoring circuit 120 includes a filtering unit 121, an energy storage unit 123, a switching unit 122, and a logic triggering unit 124. The energy storage unit 123 is connected to the first pin a1, and when the first pin a1 outputs the monitoring enable signal, the MCU110 charges the energy storage unit 123 through the first pin a1, and the monitoring circuit 120 starts to perform fault detection on the MCU 110.
The filtering unit 121 is connected to the second pin a2, and is configured to filter interference signals other than the pulse signal in the output signal of the second pin a2, for example, the output level of the second pin a2 will stop turning after the MCU110 fails, and the output level will be maintained at a high level or a low level, and the filtering unit 121 can filter the level signals, so as to ensure that the monitoring circuit 120 can be triggered when the MCU110 fails and avoid false triggering when the MCU110 normally operates.
The switch unit 122 includes a first electrical connection end, a second electrical connection end, and a third electrical connection end. The first electrical connection end of the switch unit 122 is connected to the filtering unit 121, the second electrical connection end of the switch unit 122 is grounded, and the third electrical connection end of the switch unit 122 is connected to the energy storage unit 123. The first electrical connection end of the switch unit 122 may be a control end, and the second connection end and the third electrical connection end of the switch unit 122 may be controlled to be turned on or off according to a signal input by the first electrical connection end, for example, when the first electrical connection end of the switch unit 122 inputs a high level, the second electrical connection end and the third electrical connection end of the switch unit 122 are turned on, that is, when the first electrical connection end of the switch unit 122 inputs a high level, the energy storage unit 123 is turned on with the ground end so that the energy storage unit 123 discharges to the ground; when the first electrical connection terminal of the switching unit 122 inputs a low level, the second electrical connection terminal and the third electrical connection terminal of the switching unit 122 are disconnected, that is, when the first electrical connection terminal of the switching unit 122 inputs a low level, the energy storage unit 123 is disconnected from the ground terminal, and the MCU110 charges the energy storage unit 123 through the first pin a 1.
The logic trigger unit 124 is connected to the energy storage unit 123, and an output end of the logic trigger unit 124 is used for inputting a level signal opposite to an input end thereof.
In this embodiment, when the MCU110 does not need to be monitored for faults, the first pin a1 of the MCU110 does not output a monitoring enable signal, for example, the monitoring enable signal is a high level signal, and when the MCU110 does not need to be monitored for faults, the first pin a1 of the MCU110 does not output a high level signal, i.e., the first pin a1 keeps a high impedance state or a low level state, so as not to charge the energy storage unit 123, and thus the energy storage unit 123 outputs a low level signal to the input terminal of the logic trigger unit 124, and the output terminal of the logic trigger unit 124 outputs a high level, and does not generate a falling edge signal, so as not to trigger a circuit connected to the monitoring circuit 120 to enter a fail safe alarm.
When the MCU110 needs to be monitored for faults, the first pin a1 of the MCU110 outputs a monitoring enable signal, for example, the monitoring enable signal is a high level signal, and the MCU110 charges the energy storage unit 123 through the first pin a 1. When the MCU110 normally works, the second pin a2 of the MCU110 outputs a pulse signal to the filtering unit 121, after the filtering unit 121 filters an interference signal, the switch unit 122 periodically switches on the second electrical connection terminal and the third electrical connection terminal because the first electrical connection terminal receives a periodically inverted level signal, and the energy storage unit 123 discharges to the ground when the second electrical connection terminal and the third electrical connection terminal are switched on, so that the level of the input terminal of the logic trigger unit 124 connected to the energy storage unit 123 cannot be raised, and the output terminal of the logic trigger unit 124 always outputs a high level; when the MCU110 malfunctions, the second pin a2 of the MCU110 stops outputting the pulse signal to the filtering unit 121, after the filtering unit 121 filters the interference signal, the switch unit 122 disconnects the second electrical connection terminal and the third electrical connection terminal because the first electrical connection terminal does not receive the pulse signal, and disconnects the energy storage unit 123 from the ground terminal, so that the MCU110 continuously charges the energy storage unit 123 through the first pin a1, so that the input terminal of the logic triggering unit 124 connected to the energy storage unit 123 inputs a high level, and the output terminal of the logic triggering unit 124 outputs a low level, and thus, a falling edge signal is generated as a fail-safe alarm signal, so as to trigger a fail-safe alarm entering the MCU 110.
The monitoring circuit 120 can monitor whether the MCU110 has a fault, and can generate a falling edge signal after any fault occurs in the MCU110, thereby triggering an entry to a fail-safe alarm.
In one embodiment, the charging time of the energy storage unit 123 is greater than twice the period of the pulse signal, so as to avoid false triggering.
In one embodiment, as shown in fig. 2, the MCU110 further includes a third pin A3, and the third pin A3 is a reset pin of the MCU 110. The monitoring circuit 120 further includes a trigger output unit, a reset unit, and a reverse isolation unit. The trigger output unit is connected to the output end of the logic trigger unit 124, and the trigger output unit is configured to output a fail-safe alarm signal when the output end of the logic trigger unit 124 outputs a low level, so as to trigger a fail-safe alarm entering the MCU 110. The reset unit is connected to the output end of the logic trigger unit 124 and connected to the third pin of the MCU110, and is configured to output a reset signal to the third pin a3 of the MCU110 when the output end of the logic trigger unit 124 outputs a low level, that is, the reset unit can reset the MCU110 through the reset unit after generating a falling edge signal to trigger the MCU110 to enter the fail-safe alarm, so that the system can be controlled again. The reverse isolation unit is connected between the output end of the logic trigger unit 124 and the trigger output unit and between the output end of the logic trigger unit 124 and the reset unit, and is configured to output a high level at the output end of the logic trigger unit 124, that is, perform reverse isolation on the trigger output unit and the reset unit when the MCU110 is not monitored for a fault and the MCU110 is detected for a fault and does not malfunction, so as to avoid mutual interference.
Fig. 3 is a circuit diagram of a monitoring circuit in an embodiment. With reference to fig. 1 to 3, the filtering unit 121 includes a filtering capacitor C1, and the filtering capacitor C1 is connected between the first electrical connection terminal of the switch unit 122 and the second pin a 2. The monitoring circuit 120 further includes an anti-saturation diode D1, an anode of the anti-saturation diode D1 is grounded, a cathode of the anti-saturation diode D1 is connected to the filtering capacitor C1 and connected to the first electrical connection terminal of the switch unit 122, and the anti-saturation diode D1 is used for preventing the filtering capacitor C1 from losing effect after being saturated.
Illustratively, the monitoring circuit 120 further includes a protection resistor R1. The protection resistor R1 is connected between the first electrical connection terminal of the switching unit 122 and the filtering unit 121, and is used for limiting the current of the switching unit 122.
Illustratively, the switching unit 122 includes a transistor Q1, a base of a transistor Q1 is a first electrical connection terminal of the switching unit 122, an emitter of a transistor Q1 is a second electrical connection terminal of the switching unit 122, and a collector of a transistor Q1 is a third electrical connection terminal of the switching unit 122.
Illustratively, the energy storage unit 123 includes a first voltage dividing resistor R2, an energy storage capacitor C2, and a second voltage dividing resistor R3. One end of a first divider resistor R2 is connected with the first pin A1, the other end of the first divider resistor R2 is connected with one end of an energy storage capacitor C2, the other end of the energy storage capacitor C2 is grounded, one end of a second divider resistor R3 is connected between the energy storage capacitor C2 and the first divider resistor R2, and the other end of the second divider resistor R3 is grounded. The resistance value of the second voltage-dividing resistor R3 is greater than that of the first voltage-dividing resistor R2.
Illustratively, the monitoring circuit 120 further includes a discharge resistor R6. The discharge resistor R6 is connected between the input end and the output end of the logic trigger unit 124, and the reverse isolation unit is also connected between the output end of the logic trigger unit 124 and the discharge resistor R6; when the output end of the logic trigger unit 124 outputs a low level, the discharge resistor R6 is used to shorten the discharge time of the energy storage unit 123, and when the output end of the logic trigger unit 124 outputs a high level, the reverse isolation unit performs reverse isolation on the trigger output unit, the reset unit, and the discharge resistor R6; the resistance value of the discharge resistor R6 is smaller than that of the first divider resistor R2.
Illustratively, the reverse isolation unit includes a first isolation diode D2, a second isolation diode D3, and a third isolation diode D4. The anode of the first isolation diode D2 is connected to the reset unit, and the cathode of the first isolation diode D2 is connected to the output terminal of the logic triggering unit 124. The anode of the second isolation diode D3 is connected to the trigger output unit, and the cathode of the second isolation diode D3 is connected to the output terminal of the logic trigger unit 124. The anode of the third isolation diode D4 is connected to the discharge resistor R6, and the cathode of the third isolation diode D4 is connected to the output terminal of the logic trigger unit 124.
Illustratively, the logic trigger unit 124 includes a schmitt reverse trigger U1.
Illustratively, the MCU110 also includes a power pin. The reset unit includes a first pull-up resistor R4, one end of the first pull-up resistor R4 is connected to the power pin so as to input the power voltage VDD _ MCU, and the other end of the first pull-up resistor R4 is connected to the reverse isolation unit and to the third pin A3; the trigger output unit comprises a second pull-up resistor R5, one end of the second pull-up resistor R5 is connected with the power pin so as to input the power voltage VDD _ MCU, and the other end of the second pull-up resistor R5 is connected with the reverse isolation unit.
In a specific example, as also shown in fig. 3, the monitoring circuit 120 includes a filtering capacitor C1, a protection resistor R1, an anti-saturation diode D1, a transistor Q1, a first voltage-dividing resistor R2, a second voltage-dividing resistor R3, an energy-storing capacitor C2, a discharging resistor R6, a schmitt reverse trigger U1, a first isolation diode D2, a second isolation diode D3, a third isolation diode D4, a first pull-up resistor R4, and a second pull-up resistor R5. One end of the filtering capacitor C1 is connected to the second pin a2 of the MCU110, the second pin a2 of the MCU110 outputs a pulse signal to the filtering capacitor C1 when the MCU110 is in normal operation and stops outputting the pulse signal to the filtering capacitor C1 after a fault occurs, the other end of the filtering capacitor C1 is connected to one end of the protection resistor R1, the other end of the protection resistor R1 is connected to the base of the transistor Q1 and to the cathode of the anti-saturation diode D1, the anode of the anti-saturation diode D1 is grounded, the emitter of the transistor Q1 is grounded, the collector of the transistor Q1 is connected to one end of the first divider resistor R2, one end of the second divider resistor R3 and one end of the storage capacitor C2, the other end of the storage capacitor C2 is grounded, the other end of the first divider resistor R2 is connected to the first pin a1 of the MCU110, the other end of the second divider resistor R3 is grounded, the input terminal of the schmidt reverse trigger U2 is connected between the first divider resistor R56 and the first divider resistor R8269553 and the discharge resistor 8653, the other end of the discharge resistor R6 is connected with the anode of the third isolation diode D4, the output end of the Schmidt reverse trigger U1 is connected with the cathode of the third isolation diode D4, the cathode of the first isolation diode D2 and the cathode of the second isolation diode D3, the anode of the first isolation diode D2 is connected with one end of the first pull-up resistor R4 and the third pin of the MCU, the other end of the first pull-up resistor R4 is connected with the power pin of the MCU, the anode of the second isolation diode D3 is connected with one end of the second pull-up resistor R5, and the other end of the second pull-up resistor R5 is connected with the power pin of the MCU 110.
When the fault of the MCU110 does not need to be monitored, the first pin a1 of the MCU110 does not output a monitoring enable signal, the end of the first voltage-dividing resistor R2 connected to the first pin a1 is in a low level or high resistance state, the energy-storage capacitor C2 performs RC discharge, and after the energy-storage capacitor C2 runs out of power, the input end of the schmitt reverse trigger U1 receives a low level, so that the output end of the schmitt reverse trigger U1 is always kept at a high level, and the first isolation diode D2, the second isolation diode D3, and the third isolation diode D4 cannot be turned on, thereby performing reverse isolation between the branch where the discharging resistor R6 is located, the branch where the first pull-up resistor R4 is located, and the branch where the second pull-up resistor R5 is located.
When the fault of the MCU110 needs to be monitored, the first pin a1 of the MCU110 outputs a high level to the first voltage-dividing resistor R2 as a monitoring enable signal, so that the first voltage-dividing resistor R2 and the energy-storage capacitor C2 are charged with RC, and the connection between the energy-storage capacitor C2 and the input terminal of the schmidt reverse trigger U1 maintains the high level after a period of time since the voltage of the first voltage-dividing resistor R2 and the second voltage-dividing resistor R3 is divided and the resistance of the second voltage-dividing resistor R3 is originally greater than that of the first voltage-dividing resistor R2.
Further, when the MCU110 normally operates, the second pin a2 of the MCU110 outputs a pulse signal to the filtering capacitor C1, where the pulse signal is a periodic inverted level signal. Because the filtering capacitor C1 has the ability of isolating direct current and direct current, when the level of the first pin a1 of the MCU110 is periodically inverted, a pulse signal can be output to the base of the transistor Q1 through the filtering capacitor C1 and the protection resistor R1, so that the emitter and the collector of the transistor Q1 are periodically turned on, that is, the energy storage capacitor C2 and the ground terminal are periodically turned on, and thus the electric energy in the energy storage capacitor C2 is released to the ground, so that the level of the input terminal of the schmitt reverse trigger U1 cannot be raised, and the output terminal of the schmitt reverse trigger U1 outputs a high level. Therefore, the first isolation diode D2, the second isolation diode D3 and the third isolation diode D4 cannot be conducted, and reverse isolation is performed between the branch where the discharge resistor R6 is located, the branch where the first pull-up resistor R4 is located and the branch where the second pull-up resistor R5 is located.
When the MCU fails, the second pin a2 of the MCU stops outputting pulse signals to the filtering capacitor C1, and the filtering capacitor C1 has a direct-current-crossing isolating capability, so that no signal is input to the base of the transistor Q1, and the emitter and the collector of the transistor Q1 are disconnected, i.e., the energy storage capacitor C2 is disconnected from the ground, so that the first pin a1 of the MCU110 continuously charges the energy storage capacitor C2 with electric energy until the electric energy is equal to the power voltage of the MCU110, so that the input terminal of the schmitt reverse trigger U1 is at a high level, and the output terminal of the schmitt reverse trigger U1 outputs a low level, thereby generating a falling edge signal. In addition, the first isolation diode D2, the second isolation diode D3 and the third isolation diode D4 are all turned on, so that a falling edge signal is output as a fail-safe trigger alarm signal through the anode of the second isolation diode D3, namely the output terminal X1; meanwhile, a falling edge signal is output to the third pin A3 of the MCU110 through the anode of the first isolation diode D2 as a reset signal of the MCU110, so that the MCU110 operates normally again; meanwhile, a branch where the discharge resistor R6 and the third isolation diode D4 are located provides a low-impedance discharge circuit for the energy storage capacitor C2, and since the resistance value of the discharge resistor R6 is much smaller than that of the first voltage-dividing resistor R2, the discharge time can be shortened, so that the MCU110 can be reset quickly.
The application also provides a constant current driving device. As shown in fig. 2, the constant current driving apparatus includes a constant current driving module 130, an MCU110, and a monitoring circuit 120 as in any one of the above embodiments. The MCU110 is connected with the constant current driving module 130 and the monitoring circuit 120, the constant current driving module 130 is further connected with the monitoring circuit 120, and the constant current driving module 130 is further connected with the load 140; the MCU110 is configured to control the constant current driving module 130 to perform constant current driving on the load 140, and the monitoring circuit 120 is configured to monitor whether the MCU110 fails and output a falling edge signal to the constant current driving module 130 when the MCU110 fails to perform a fail-safe alarm.
The monitoring circuit 120 may further output a reset signal to the MCU110 after the MCU110 has failed so that the MCU110 is reset, when the MCU110 is reset, the first pin a1 of the MCU110 is in a high impedance state, the monitoring circuit 120 stops working, and after the MCU110 is restarted, the monitoring circuit 120 outputs a monitoring enable signal and a pulse signal again, and reconfigures the constant current driving module 130 so that the constant current driving device 130 returns to a normal working state.
The application also provides a car light. The vehicle lamp includes an LED module and the constant current driving device as in any one of the above embodiments. The constant current driving device is connected to the LED module and configured to drive the LED module to light up, that is, the load 140 is an LED module.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (13)
1. A monitoring circuit is characterized in that the monitoring circuit is used for being connected with an MCU (microprogrammed control unit) and generating a falling edge signal after the MCU fails to serve as a failure safety alarm signal, the MCU comprises a first pin and a second pin, the first pin is used for outputting a monitoring enabling signal when the MCU needs to be monitored whether the MCU fails, the second pin is used for outputting a pulse signal and stopping outputting the pulse signal when the MCU fails, and the pulse signal is a periodic turnover level signal; the monitoring circuit includes:
the filtering unit is connected with the second pin and is used for filtering interference signals except the pulse signals in the output signals of the second pin;
the energy storage unit is connected with the first pin, and the MCU charges the energy storage unit through the first pin when the first pin outputs the monitoring enabling signal;
the first electric connection end of the switch unit is connected with the filtering unit, the second electric connection end of the switch unit is grounded, and the third electric connection end of the switch unit is connected with the energy storage unit; the switch unit is used for controlling the connection or disconnection between the second electric connection end and the third electric connection end according to a signal input by the first electric connection end; and
and the output end of the logic trigger unit is used for outputting a level signal opposite to the input end of the logic trigger unit.
2. The monitoring circuit of claim 1, wherein the MCU further comprises a third pin, the third pin being a reset pin of the MCU, the monitoring circuit further comprising:
the trigger output unit is connected with the output end of the logic trigger unit and is used for outputting the fault safety alarm signal when the output end of the logic trigger unit outputs a low level;
the reset unit is connected with the output end of the logic trigger unit, connected with the third pin and used for outputting a reset signal to the third pin when the output end of the logic trigger unit outputs a low level;
and the reverse isolation unit is connected between the output end of the logic trigger unit and the trigger output unit, is connected between the output end of the logic trigger unit and the reset unit, and is used for performing reverse isolation on the trigger output unit and the reset unit when the output end of the logic trigger unit outputs a high level.
3. The monitoring circuit according to claim 2, wherein the filtering unit comprises a filtering capacitor, and the filtering capacitor is connected between the first electrical connection terminal of the switch unit and the second pin;
the monitoring circuit still includes prevents the saturation diode, prevent the anode ground connection of saturation diode, prevent the saturation diode the cathode with filtering electric capacity is connected and with the first electricity of switch element connects, prevent the saturation diode and be used for preventing lose effect after the filtering electric capacity is saturated.
4. The monitoring circuit of claim 2, further comprising:
and the protection resistor is connected between the first electric connection end of the switch unit and the filtering unit and used for limiting the current of the switch unit.
5. The monitoring circuit of claim 2, wherein the switch unit comprises a transistor, a base of the transistor is a first electrical connection terminal of the switch unit, an emitter of the transistor is a second electrical connection terminal of the switch unit, and a collector of the transistor is a third electrical connection terminal of the switch unit.
6. The monitoring circuit of claim 2, wherein the energy storage unit comprises a first voltage dividing resistor, an energy storage capacitor and a second voltage dividing resistor; one end of the first divider resistor is connected with the first pin, the other end of the first divider resistor is connected with one end of the energy storage capacitor, the other end of the energy storage capacitor is grounded, one end of the second divider resistor is connected between the energy storage capacitor and the first divider resistor, and the other end of the second divider resistor is grounded;
the resistance value of the second voltage-dividing resistor is larger than that of the first voltage-dividing resistor.
7. The monitoring circuit of claim 6, further comprising:
the discharge resistor is connected between the input end and the output end of the logic trigger unit, and the reverse isolation unit is also connected between the output end of the logic trigger unit and the discharge resistor; when the output end of the logic trigger unit outputs a low level, the discharge resistor is used for shortening the discharge time of the energy storage unit, and when the output end of the logic trigger unit outputs a high level, the reverse isolation unit performs reverse isolation on the trigger output unit, the reset unit and the discharge resistor;
wherein the resistance value of the discharge resistor is smaller than that of the first voltage dividing resistor.
8. The monitoring circuit of claim 7, wherein the reverse isolation unit comprises:
the anode of the first isolation diode is connected with the reset resetting unit, and the cathode of the first isolation diode is connected with the output end of the logic triggering unit;
the anode of the second isolation diode is connected with the trigger output unit, and the cathode of the second isolation diode is connected with the output end of the logic trigger unit;
and the anode of the third isolation diode is connected with the discharge resistor, and the cathode of the third isolation diode is connected with the output end of the logic trigger unit.
9. The monitoring circuit of claim 2, wherein the logic trigger unit comprises a schmitt-reverse trigger.
10. The monitoring circuit of claim 2, wherein the MCU further comprises a power supply pin;
the reset unit comprises a first pull-up resistor, one end of the first pull-up resistor is connected with the power pin, and the other end of the first pull-up resistor is connected with the reverse isolation unit and the third pin;
the trigger output unit comprises a second pull-up resistor, one end of the second pull-up resistor is connected with the power pin, and the other end of the second pull-up resistor is connected with the reverse isolation unit.
11. The monitoring circuit of claim 1, wherein the charging time of the energy storage unit is greater than twice the period of the pulse signal.
12. A constant current driving device, comprising an MCU, a constant current driving module, and the monitoring circuit according to any one of claims 1 to 11; the MCU is connected with the constant current driving module and the monitoring circuit, and the constant current driving module is also connected with the monitoring circuit; the monitoring circuit is used for monitoring whether the MCU breaks down and outputting a falling edge signal to the constant current driving module to carry out fault safety alarm when the MCU breaks down.
13. A vehicle lamp, characterized by comprising:
an LED module; and
the constant current driving device as claimed in claim 12, connected to the LED module for driving the LED module to light up.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022732264.XU CN213783652U (en) | 2020-11-23 | 2020-11-23 | Monitoring circuit, constant current drive device and car light |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022732264.XU CN213783652U (en) | 2020-11-23 | 2020-11-23 | Monitoring circuit, constant current drive device and car light |
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| Publication Number | Publication Date |
|---|---|
| CN213783652U true CN213783652U (en) | 2021-07-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202022732264.XU Active CN213783652U (en) | 2020-11-23 | 2020-11-23 | Monitoring circuit, constant current drive device and car light |
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| Country | Link |
|---|---|
| CN (1) | CN213783652U (en) |
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2020
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